Sealing system for exhaust-gas lines

ABSTRACT

A sealing system, in particular for sealing multiple-part exhaust-gas lines for an internal combustion engine, having at least a first ( 9 ) and a second flange part ( 11 ) which guides a flow of heat ( 5 ), which flange parts ( 9, 11 ) delimit a receiving space ( 33 ) for at least one sealing element ( 31 ) between them, is characterized in that the flange parts ( 9, 11 ) which adjoin one another in each case form an outwardly projecting annular flange ( 13 ) which faces away from the flow of beat ( 5 ), extends transversely with respect to the former and in which chambering of the receiving space ( 33 ) is formed for the sealing element ( 31 ) by an annular groove ( 45 ) which is open at the end face ( 17 ) of at least one flange part ( 11 ) and is recessed axially into said end face ( 17 ), and in that at least one covering element ( 47 ) is arranged in the annular groove ( 45 ), which at least one covering element ( 47 ) forms thermal shielding for the at least one sealing element ( 31 ) at least on its side which faces the end face ( 17 ) of the flange part ( 11 ).

The invention relates to a sealing system, in particular for sealing of multipart exhaust-gas lines for an internal combustion engine, having at least one first and one second flange part which conduct a heat flow and which between themselves delimit a receiving space for at least one sealing element.

Sealing systems of this type are known. DE 10 2004 060 845 A1 shows, for example, such a sealing system for the exhaust gas line of a reciprocating piston engine, the sealing element being a metallic gasket in the form of a profile body with a C-shaped profile cross section. Sealing elements on exhaust gas lines are subject to very high temperatures which can exceed 600° C. Even if materials are used with properties that are suitable with respect to heat resistance, the sealing elements at the prevailing high operating temperatures lose their functional properties which are required for sealing, especially the elasticity of the sealing elements is reduced by creep processes due to overly high thermal loads.

Accordingly, the object of the invention is to provide a sealing system which, when used in a hot gas region, ensures reliable sealing even when high temperatures occur on the exhaust gas lines to be sealed.

According to the invention, this object is achieved by a sealing system which has the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the flange parts which are to be sealed against one another form an annular flange which faces away from the heat flow and which projects transversely to the latter to the outside, and in which chambering is formed for the pertinent sealing element, the material of the annular flange itself already forms a certain thermal shielding of the sealing element relative to the heat flow. In that, moreover, the sealing element, which has been chambered in the annular groove, is additionally protected by means of a cover element which within the annular groove forms thermal shielding at least on the side of the sealing element which faces the end face of the flange part, i.e., on the open side of the annular groove which is thermally most heavily loaded, the sealing element is protected especially effectively against overly high thermal loads such that the system according to the invention can also be reliably used on exhaust gas lines which are thermally highly loaded.

Preferably, the cover element is a metallic annular body.

When there is an annular body in the form of a flat ring, it is preferably inserted such that it extends between the sealing element and the facing end face of the flange part and thus forms a thermal barrier on the region of the annular groove which is most heavily thermally loaded and in which the sealing element is chambered.

Instead of a flat annular body, the cover element can be formed by a profile ring which, for example, can have an arched profile or an angled profile.

In such embodiments the annular body is preferably inserted into the annular groove such that it surrounds the sealing element both on the side facing the end face and also on the side which is facing another wall of the receiving space.

Especially good thermal shielding of the sealing element in such embodiments can be achieved when the cover element also surrounds the sealing element on the side nearest the heat flow, that is, on that side which faces the radially inside wall of the annular groove.

The sealing element is preferably a molded ring seal, with a C-shaped or V-shaped profile cross section. In this case, the sealing element with the C-profile is preferably installed in the annular groove such that the profile is open radially to the inside, that is, towards the pressure side of the system.

Instead of a V-shaped or C-shaped profile cross section, the sealing element could also have a meandering profile cross section, in the form of a bellows solution in which several folds lying on top of one another form the cross section.

Alternatively, metal bead seals can be installed in the receiving space. In any case, the invention ensures thermal protection for the respective sealing element so that for metallic sealing elements of a material which is available for high temperature use, reliable sealing in hot gas regions is ensured. The annular shape for the sealing element can be circular or nearly circular. Furthermore, ring shapes are conceivable in the form of an oval or a rectangular shape, preferably with rounded corner regions. An assignable annular groove must then preferably follow the pertinent ring shape of the sealing element.

The invention is detailed below using embodiments shown in the drawings.

FIG. 1 shows a longitudinal section of adjacent line sections of an exhaust gas line, drawn highly schematically simplified, broken away and half-side, the line sections being mutually sealed by a sealing system according to one embodiment of the invention;

FIG. 2 shows a half-side longitudinal section of only the junction region of the adjacent flange parts of two line sections, provided with a second embodiment of the sealing system,

FIG. 3 shows a representation similar to FIG. 2, provided with a third embodiment of the sealing system.

In the figures, a first line section and a second line section of an exhaust gas line are designated as 1 and 3, respectively. In the operation of the pertinent internal combustion engine, the exhaust gas line conducts an exhaust gas-heat flow 5 with a correspondingly high exhaust gas temperature. The line sections 1 and 3 which are to be sealed against one another by means of the sealing system according to the invention and which are to be connected to one another each have a flange part 9 and 11 respectively which projects radially to the outside relative to the axis 7 of the line. The flange parts 9 and 11 together form an annular flange 13, the flange parts 9 and 11 having end faces 15 and 17 which face one another. In order to connect the line sections 1 and 3 to one another, the flange parts 9, 11 of the annular flange 13 are braced to one another by suitable clamping means which may be conventional and which are therefore not shown. For example, the clamping means could be a clamping ring which has been pulled onto peripheral bevels 25 of the flange parts 9 and 11 (not shown).

The figures show as the sealing element for sealing between the flange parts 9 and 11 a metallic molded ring seal 31 with a C-shaped profile cross section. As indicated above, a molded ring seal with a different profile cross section or a bead seal or the like could be used. In any case, the pertinent sealing element is at least partially chambered in a receiving space 33 formed between the flange parts 9 and 11. As shown in the drawings, in the embodiments as shown in FIGS. 1 to 3 the receiving space 33 is formed by a respective annular groove 45 which is machined recessed in the axial direction in the flange part 11 from its end surface 17, in conjunction with the end face 15 of the flange part 9, closed chambering for the molded ring seal 31 being formed.

According to the invention, additional heat protection for the molded ring seal 31 which is located in the receiving space 33 is a cover element 47 which has been inserted into the annular groove 45. The cover element 47 is made such that it forms a thermal barrier between the molded ring seal 31 and the thermally most heavily loaded region of the receiving space 33. In the embodiment of FIG. 1, the cover element 47 is formed by a flat metal ring which is inserted between the molded ring seal 31 and the end surface 17 which borders the end face 15 of the opposite flange part 9. As the flow arrow 49 indicates, this junction site is most heavily under the influence of the heat flow 5 so that the cover element 47 has the greatest protective effect in this position.

In the embodiment of FIG. 2, instead of a flat ring the cover element 47 has an arched annular body which is installed in the annular groove 45 such that it shields not only that side of the molded ring seal 31 which borders the open side of the annular space 45 and forms a barrier there in the same manner as in the example of FIG. 1, but, moreover, with an arched region extends over the molded ring seal 31 such that it is also shielded relative to the radially inner wall of the annular groove 45, i.e., against the wall of the receiving space 33 which is nearest the heat flow 5.

FIG. 3 illustrates another embodiment in which the cover element 47 likewise forms a shield on two sides of the molded ring seal 31. For this purpose, the cover element 47 is made as an angled profile ring, a profile leg, analogously to the flat annular body of FIG. 1, extending along the junction site between the end faces 17 and 15. The angled other profile leg opposite thereto, now in correspondence to the arched profile part of the cover element 47 of FIG. 2, in turn forms the shielding relative to the wall of the receiving space 33 which is nearest the heat flow 5.

It goes without saying that instead of the illustrated forms of the cover element 47, other profile cross sections could be used, for example, a U profile which surrounds the sealing element along three sides. In any case, the cover element 47 is installed in the annular groove 45 such that the molded ring seal 31 is covered at least on the side which is facing the junction site between the end faces 15 and 17 of the flange parts 9 and 11, preferably, in addition, the correspondingly shaped cover element 47 extending over the molded ring seal 31 on at least one other thermally endangered site. 

1. A sealing system, in particular for sealing of multipart exhaust gas lines for an internal combustion engine, having at least one first (9) and one second flange part (11) which conduct a heat flow (5) and which between themselves delimit a receiving space (33) for at least one sealing element (31), characterized in that the flange parts (9, 11) which are respectively adjacent to one another form an annular flange (13) which projects to the outside, which faces away from the heat flow (5), which runs transversely to the latter, and in which chambering of the receiving space (33) for the sealing element (31) is formed by an annular groove (45) which is open on the end face (17) of at least one flange part (11) and which is axially recessed therein, and that in the annular groove (45) there is at least one cover element (47) which forms thermal shielding for at least one sealing element (31) at least on its side facing the end face (17) of the flange part (11).
 2. The sealing system according to claim 1, characterized in that the cover element is a metallic ring body (47).
 3. The sealing system according to claim 2, characterized in that the cover element is a flat annular body (47) which is inserted between the sealing element (31) and the end face (17).
 4. The sealing system according to claim 2, characterized in that the cover element is an annular body (47) with an arched profile.
 5. The sealing system according to claim 2, characterized in that the cover element is an annular body (47) with an angled profile.
 6. The sealing system according to claim 4, characterized in that the annular body (47) is inserted into the annular groove (45) such that it surrounds the sealing element (31) both on the side facing the end face (17) and also on the side which is facing another wall of the receiving space (33).
 7. The sealing system according to claim 6, characterized in that the annular body (47) surrounds the sealing element (31) and also on the side nearest the heat flow (5).
 8. The sealing system according to claim 1, characterized in that the sealing element is a molded ring seal (31 ) with a C-shaped or V-shaped profile cross section.
 9. The sealing system according to claim 8, characterized in that the molded ring seal (31) is installed in the annular space (45) such that the C-profile is open radially to the inside. 